<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>flex study</title>
		<style>
			.parent{display: flex;justify-content: center;align-items: center;width: 100%;height: 500px;background: #2D93CA;}
			.son{width:200px;height: 200px;background: #FFF000;}
		</style>
	</head>
	<body>
		<div class="parent">
			<div class="son" ></div>
		</div>
	</body>
</html>
